Crankcase lubricant compositions



United States Patent ()fiice 3,655,839 Patented Sept. 25, 1962 3,655,830 CRANKCASE LUBRIQANT CQMPQSKTIGNS Daniel A. Hirschler, J12, Birmingham, Mich, assignor to Ethyl Corporation, New York, N.Y., a corporation of Delaware No Drawing. Filed Dec. 17, 1953, Ser. No. 780,928 1 Claim. (Cl. 252-5) This invention relates to improved engine crankcase lubricant compositions which are particularly eifective in minimizing both octane requirement increase and engine deposit weight. This application is a continuation-impart of my co-pendiug application, Serial No. 559,522, filed January 17, 1956, now abandoned, which in turn is a continuation-in-part of application, Serial No. 304,858, filed August 16, 1952, and now abandoned.

During the operation of spark ignition internal combustion engines, deposits are formed in combustion chambers and on associated engine parts, particularly when the engines are operated under conditions of low speed and light load. Such deposits are composed of decomposition products of the crankcase lubricating oil and the fuel.

Engine deposits bring about the problem of octane requirement increase. During the accumulation of engine deposits, the octane number requirement of the engine increases until a point of equilibrium in deposit formation is reached. Thus, a clean engine-Le, an engine containing no deposits-may have an octane requirement in the order of 70, Whereas when deposit accumulation in the engine has reached the point of equilibrium, the octane requirement may be in the order of 80. The difference between these octane requirements is termed the octane requirement increase. In some cases, this increase may be as high as numbers.

The problems of octane requirement increase and excessive combustion chamber deposit formation are not necessarily related. For example, it is possible to reduce the gross weight of combustion chamber deposits Without affecting octane requirement increase. In fact, the reduced amount of remaining deposits may actually further increase the octane requirement of the engine. Thus, to effectively combat the octane requirement increase problem, it definitely appears necessary to alter the makeup and characteristics of the deposits. Merely reducing the level of deposition is oftentimes not enough. For instance, fleet tests where vehicles Were operated on a schedule consisting of about 70 percent urban service and about percent rural service showed that there was no direct correlation between combustion chamber deposit weight and octane requirement increase. In one group of 21 cars the average octane requirement increase was 10.1 and the average combustion chamber deposit weight, grams per engine, was 62.1. But, in another group of 22 cars (same makes and models) the average octane requirement increases was 10.8 even though the average combustion chamber deposit weight was only 44.0 grams per engine.

Excessive engine deposits are very undesirable from other standpoints, however. They cause loss in engine power; malfunctioning of valves; plugging of piston rings; increase in oil consumption; and, to a greater or lesser degree, malfunctioning of the engine. Deposits formed in the modern, high compression, gasoline engine operated on leaded gasoline are especially difiicult to deal with as they are less organic in nature than deposits formed in the low compression engines used years ago.

These two engine deposit problemsoctane requirernent increase and excessive engine deposit formation have long existed in the art. The octane requirement increase problem has been particularly persistent. Despite early recognition of it as a problem and the longstanding realization that a solution of it would be great advance in 2 the art, very few additives have been proposed and found to have any effectiveness against octane requirement increase. Unfortunately, those few additives having a bencficial effect on the problem possessed so many shortcomings as to be totally impractical.

Among the objects of this invention is that of providing improved crankcase lubricant compositions which minimize both octane requirement increase and deposit weight in spark ignition engines operated on leaded gasoline. Other objects of this invention will be apparent from the ensuing description.

I have found that the above and other objects of this invention are accomplished by providing an improved crankcase lubricating oil composition especially adapted to minimize octane requirement increase and combustion chamber deposit weight in spark ignition internal combustion engines operated on leaded gasoline, which composition consists essentially of (1) a halogen-free crankcase lubricating oil having a viscosity index of at lea-st 100, a viscosity at F. of at least Saybolt Universal seconds, and a viscosity at 210 F. of 40 to 70 Saybolt Universal seconds; and (2) from about 3 to about 15 percent by weight based on the weight of the oil of a compound selected from the group consisting of diphenyl and 1,2,3,4- tetrahyd-ronaphthalene. It has been found by actual engine tests that crankcase lubricating oil compositions as defined above result in minimization of octane requirement increase and in the formation of smaller amounts by weight of engine deposits.

The additives used in the improved crankcase lubricants of this invention are available as articles of commerce and the methods of preparing them are well known in the art. Another important advantage of these additives is that they do not cause any adverse eifects upon either the base crankcase oil in which they are dissolved or the engine in which my novel crankcase lubricants are used.

The crankcase lubricating oil used in the improved lubricants of this invention is halogen free. In other words, the crankcase lubricating oil does not contain ingredients which contain halogen. If halogen is present in more than trace amounts in the crankcase lubricating oil, the effectiveness of the additives of this invention is markedly impaired. The halogen-free crankcase lubricating oil can be derived from natural crude oil, that is, mineral oil or can be a synthetic crankcase lubricant. The crankcase lubricating oil used in the improved crankcase lubricants of this invention should have an SAE viscosity number ranging from SAE 5W to SAE 30*. For further details concerning the classification of SAE viscosity numbers, see Society of Automotive Engineers Handbook, 1955, pages 356357.

Special base oils are used in formulating my crankcase lubricants. In the first place, they must be that type of oil known and classified in the art as a crankcase lubricating oil for spark-ignition engines. These oils are commonly referred to as motor oils. Thus, they should not be confused with other types of engine or industrial oils which are (1) designed to meet individual specifications applicable to their intended use, 2) produced by refining and blending procedures which are different from those used in crankcase lubricating oil manufacture, and (3) separately classified as to composition, properties and function by those skilled in the art. In other words, my invention is applicable only to crankcase lubricating oils for spark-ignition engines. All other oils are not only different from these crankcase lubricating oils, but are inapplicable to my invention. Furthermore, I use special types of crankcase lubricating oils. They must possess the viscosity and viscosity index properties set forth above. In this Way, the exceedingly important technical advantages of this invention are fully realized. Thus, the very special crankcase lubricating oils used per this invention are, as a group, very far removed as regards composition, properties and function from such lubricants as engine preservative oils, steam turbine lubricants, transformer oils, steam cylinder oils, and so on. Therefore, in order to effectively practice this invention, it is essential to observe the foregoing limitations and distinctions.

Another unique feature of this invention is the specificity of my additives. The important benefits caused by the presence of my additives in the above specific crankcase lubricating oils-reduced octane requirement increase and combustion chamber deposit weight-are not given by a large number of other carbocy-clic compounds. In fact, many such other compounds actually are deleterious in either or both of these respects. For instance, decahydronaphthalene, pyrene, phenanthrene, and many other such materials have been shown to increase the severity of one or both of the octane requirement increase and deposit weight problems.

The following examples illustrate the general methods of compounding the improved lubricating oil compositions of this invention.

EXAMPLE I To 14.6 pounds of phenol-treated, halogen-free mixed base mineral crankcase lubricating oil having a viscosity of 307 Saybolt Universal seconds (SUS) at 100 F. and 53.4 SUS at 210 F. and having a viscosity index (VI) of 103 was added 1.62 pounds of tetralin (1,2,3,4-tetr-ahydronaphthalene). The resulting blend was intimately mixed producing a homogeneous-improved crankcase lubricant containing 11.1 percent by weight of :tetr-alin.

EXAMPLE II To 14.6 pounds of phenol-treated, halogen-free mixed base mineral crankcase lubricating oil having a viscosity of 307 SUS at 100 F7 and 53.4 SUS at 210 F. and having a viscosity index (VI) of 103 was added 1.65 pounds of diphenyl. The resulting mixture was then heated to a temperature in the order of about 180 F. with continuous stirring producing a homogeneous-improved crankcase lubricant containing 11.3 percent by Weight of diphenyl.

EXAMPLE III With 1000 parts by weight of a conventionally-refined Pennsylvania neutral crankcase lubricating oil having a VI of 100 and Saybolt viscosity of 206 at 100 F. and 47.0 at 210 F. is mixed 140 parts by weight of 1,2,3,4- ltetrahydronaphthalene.

EXAMPLE IV With 1000 parts by weight of a commercial multigraded 10W-20 motor oil having a VI of 138 and a Saybolt viscosity of 239 SUS at 100 F. and 55 SUS at 210 F. is blended 30 parts by weight of diphenyl.

EXAMPLE V The procedures of Examples l-IV inclusive are repeated using the following crankcase lubricating oils: (1) SAE W-20 motor oil having a viscosity at 100 F. of 178.8 SUS and at 210 F. of 52.0 SUS, and a VI of 154.2; (2) SAE l0W-30 motor oil having a viscosity at 100 F. of 315.3 SUS and at 210 F. of 63.0 SUS, and a VI of 138.9; (3) SAE W-30 motor oil having a viscosity at 100 F. of 335.4 SUS and at 210 F. of 68.4 SUS, and a VI of 144.4; and SAE 30 solvent-extracted Pennsylvania crankcase lubricating oil having a viscosity at 100 F. of 500 SUS and at 210 F. of 67.0, and a VI of 110. The resultant lubricants give reductions in octane requirement increase and deposit weight when used as crankcase lubricants in passenger cars operated on leaded gasoline.

To demonstrate the effectiveness of my improved crankcase lubricant compositions in minimizing octane requirement increase and deposit weight, many comparative engine tests were conducted. The test method involves opcrating a single-cylinder Coordinating Fuel Research (CFR) enginewhich has been freed of engine depositsunder relatively mild cycling conditions for deposit formation and making periodic determinations of octane number requirement. At the completion of the test, the weight of engine deposits which have formed is determined.

The test engine is operated for 165 hours on a cycling schedule alternating between the following conditions:

Duration, seconds 50-150.

Speed, rpm 600:30-900.

Load Nonefull.

Fuel/air ratio 0087:0004-0070:0001. Ignition timing TDC-TDC.

Coolant temp, F. 148i3-148i3.

Oil temp, F 160:5-160i5.

Carburetor intake air, F. 110:5-110i5.

To determine octane number requirement, the engine is operated under the conditions of the full throttle portion of the test cycle. Reference fuel blends of isoootane and normal hept ane are used. Knock determinations are made by ear as the ignition timing is varied to the point of trace knock. Three or more reference fuel blends which knock between 5 ATC (after top dead center) and 15 BTC (before top dead center) are rated and the requirement of the top dead center is interpolated from the plot of these data. Upon completion of the test, the engine is dismantled and all engine deposits formed in the combustion chamber and on associated engine parts are removed and weighed.

In the following tests the above engine was operated on a fuel consisting of isooctane containing 3.0 milliliters of tetraethyllead per gallon as an antiknock fiuid composition consisting essentially of tetraethyllead, 0.5 theory of bromine as ethylene dibromide and 1.0 theory of chlorine as ethylene dichloride. A theory of these halogens is defined as the quantity theoretically required to react with the lead to form the corresponding lead dihalide-in this instance, lead bromide (PbBr and lead chloride (P 1901 In the following tests the crankcase lubricant comprised :a halogen-free, phenol-treated mixed base mineral oil having a viscosity of 307 SUS at F. and 53.4 SUS at 210 F., and having a viscosity index of 103. This mineral oil was commercially available and initially contained no additives.

The above-described test procedure was conducted using the above fuel and additive-free crankcase lubricant to establish equilibrium values for octane requirement and weight of engine deposits. These values represent the values obtained in control tests and are referred to herein as the baseline values.

Individual portions of the above crankcase lubricant containing the additives of this invention were employed in the engine under the test conditions specified above. Since everything was held constant except for the additive in the crankcase lubricant, the test accurately measured the effects on octane requirement and deposit weight brought about by the additives of this invention. For comparative purposes, the same additive-free crankcase lubricant was treated with other aromatic compounds, namely, dichloronaphthalene, l-methylnaphthalene, phenanthrene, pyrene, decahydronaphthalene, and an aromatic-rich fraction obtained from a commercial naphthenic base lubricating oil by extraction of this oil with aniline. Where a crankcase oil additive was used, the result with respect to octane requirement increase and deposit Weight were expressed in terms of percent of the baseline or control value. Thus, an additive was effective from either or both of these standpoints if its rating in terms of percent of baseline was less than 100. On the other hand, where an additive resulted in a number greater than 100, it produced an adverse effect. The results of these engine tests are shown in the table.

TABLE.Efiect of Crankcase Lubricating Oil Additives on Engine Performance Octane Reqnire- Deposit Additive ment Weight, Test No. Additive Cone, Increase, Percent wt. Percent of Percent of Baseline Baseline 1 None 100 100 ADDITIVES OF THIS INVENTION Diphenyl 11. 3 74 86 1,2,3,4-Tetrahydronaphtha- 11. 1 86 79 lene.

ADDITIVES NOT OF THE INVENTION Dichloronaphthalene 14. 1 114 123 l-Methylnaphthalene 11. 7 80 118 Phenanthrene 3. 0 124 129 Pyrene 3. 0 110 126 Decahydronaphthalene 8.8 105 90 Aromatic-rich lubricating 7.1 141 147 oil traction.

Obtained by extracting a commercially-available naphthenic base crankcase lubricating oil with aniline.

Referring to the data appearing in the table, it is obvious that the additives of this invention cause a substantial reduction in octane requirement increase and in deposit weight. In contrast, dichloronaphthalene, phenanthrene, pyrene and the aromatic-rich fraction caused decidedly inferior results on both octane requirement increase and deposit weight. l-methylnaphthalene does cause a reduction in octane requirement increase, but on the other hand, produces a significant increase in the Weight of engine deposits formed. Conversely, decahydronaphthalene made the octane requirement increase problem Worse even though it had some beneficial efiect on deposit Weight. It is :thus clear that the compositions The crankcase lubricating oil compositions of this inverrtion may contain other additives so long as these materials do not contain halogen. Thus, the crankcase lubricants of this invention may contain such materials as viscosity index irnprovers (e.g., acrylates and methacrylates), roam depressants, detergent-dispersants, pour point depressants, and the like, so long as these materials do not contain halogen. My crankcase lubricating oil addiwives are elfective in both synthetic and natural crankcase lubricating oils, such as naphthenic oils, parafilnic oils and mixed base oils, as long as the oil is essentially halogen tree and has the properties set forth above.

I claim:

In the method of operating a spark ignition internal combustion engine which is lubricated with a crankcase lubricating oil and wherein leaded gasoline is introduced into the combustion chambers of the engine and ignited therein, the improvement which comprises lubricating said internal combustion engine with a crankcase lubricating oil composition especially adapted to minimize octane requirement increase and combustion chamber deposit Weight in said engine, which composition consists essentially of (1) a halogen-free crankcase lubricating oil having a viscosity index of at least 100, a viscosity at F., of at least Saybolt Universal seconds and a viscosity at 210 F. of 40 to 70 Saybol-t Universal seconds; and (2) from about 3 to about 15 percent by Weight based on the Weight of the oil of diphenyl.

References Cited in the file of this patent UNITED STATES PATENTS 1,749,244 Fessler Mar. 4, 1930 1,918,593 Dow July 18, 1933 2,167,064 Dietrick July 25, 193.9 2,217,368 Horsch Oct. 8, 1940 2,592,435 Lacombl Apr. 8, 1952 FOREIGN PATENTS 760,861 France Dec. 27, 1933 

